Wheel cylinder bore size question

Discussion in 'Brakes for your Classic Mopar' started by gliderider06, Nov 6, 2018.

  1. gliderider06

    gliderider06 Well-Known Member

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    I was going to buy new rear wheel cylinders, for rear brakes, on my 87 Ramcharger. Rockauto has 2 different bore sizes available for my brakes. 7/8 & 1-1/16. What's the difference? Does one give more braking power over the other? Confused on which set to get.
    Thanks Paul
     
  2. OL DODGE

    OL DODGE Well-Known Member

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    Does your Ramcharger have 11 x 2 1/2" brakes ? Most did and that would take a 15/16" bore cylinder Raybestos # WC37235 (same left and right) : You want the correct bore because that will change the braking characteristics a lot . The vehicle was designed to work with a certain area of friction material , a certain wheel cylinder size , certain hardware - it's like having a cam in the engine working with the correct intake,carb, etc,,,,
     
  3. gliderider06

    gliderider06 Well-Known Member

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    My Ramcharger has 12x3 rear brakes. Rockauto had both wheel cylinders listed for the 12x3 brakes. That's what confused me and i didn't complete the order until I find out.
    Thanks Paul
     
  4. mbaird

    mbaird mbaird FABO Gold Member

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    larger bore = more stopping power and more pedal travel.

    Do you have power brakes ? If so I would go with smaller bore 7/8
     
  5. mbaird

    mbaird mbaird FABO Gold Member

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    Hmmm.... I was selling Dodges in 87 and cannot remember if manual brakes were available.. probably were... I wish I had kept some Data books !
     
  6. gliderider06

    gliderider06 Well-Known Member

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    I do have power brakes. I'm not sure if they had manual brakes on Ramchargers. I think they were all power brakes.
     
  7. RustyRatRod

    RustyRatRod Just another dumbass. FABO Gold Member

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    That's a 3/16 difference.
     
  8. mbaird

    mbaird mbaird FABO Gold Member

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    as recent as 87 seems to some of us...lol. You would be surprised at how many things were options then. Those Data books were big ! You could still order almost anything ! We were still ordering slant 6 , 4 sp , rubber mat , vinyl seat base trucks... Radio and heater deletes were still available. Steel wheels with poverty caps were common.
     
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    • gliderider06

      gliderider06 Well-Known Member

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      Did some more digging... 7/8 Is for 12x2.5 and 1-1/16 Is for 12 x 3"
       
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      • mbaird

        mbaird mbaird FABO Gold Member

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        Interesting that the more powerful one is used with the larger surface area drum...
        might have been a 360 vs /6 or towing package decision.
        I believe there were different GVWs as well for AW150s... but all were 1/2 tons.
         
      • jas0162

        jas0162 Well-Known Member

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        Does your truck have that big brake on a 9 1/4 half ton rear end? Usually the 12 x 3 brake is on one ton trucks with the Dana 60/70 type rear end. Either way use the bigger wheel cylinder
         
      • roccodart440

        roccodart440 Well-Known Member

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        Just for reference I use 7/8 with manual brakes. Easier to push pedal, more peddle travel. (AKA poor mans power brakes)

        I'd use larger than 7/8